OT-B - Is there a way to reduce Spindle Acceleration / Current Draw?

[simonrafferty]

I have a Denford Cyclone which I'm running from a 10kW 3 Phase Converter. The rating plate on the machine is 27HP (roughly 20kW)

It works pretty well - except when you spin up the spindle too fast.

It will run up to 1500 from 0 in one step without a problem but if you say go from 0 to 2000, it trips out due to the mains voltage dipping.
You can start from 1500 and increase it gradually in steps of 200 RPM up to 5000 RPM - and it stays happy, even when cutting.

The spindle acceleration is very fast - a fraction of a second to reach 1500.

Is there a parameter which will reduce the acceleration? I've looked through the parameter manual and the only two that stand out are
0110 - Delay Timer to check the spindle speed arrival signal
0584 - Spindle loop gain

0110 is set to 255
0584 is set to 75

Most sources I've found say not to adjust the loop gain. I'm not convinced the issue is that it checks the spindle arrival - and it hasn't. Often the machine completely shuts down if you spin-up too fast requiring a power cycle.

What would you recommend?

I can't fit a higher power Phase Converter as the mains supply to my Workshop is only 50A @ 230V ~ 11.5kW and I'm not keen to blow the main fuse.

Thanks in advance,

Si

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[drdos]

Some spindle amplifiers have adjustments for acceleration and deceleration. You may check yours and see if you have that capability.

[simonrafferty]

Some spindle amplifiers have adjustments for acceleration and deceleration. You may check yours and see if you have that capability.

Thanks Dr Dos - I hadn't thought of that. I had assumed that everything would be set through the machine parameters. Obvious when I think about it! (Doh!)

Just in case it helps anyone else, the Spindle Controller is a Fanuc A06B-6059-H002 #H501 as pictured.
I found the manual here: https://s3.amazonaws.com/Icarus/DOCU...nuals_1793.pdf

And there does indeed seem to be a spindle acceleration time parameter. The manual says it defaults to 5 Sec 0 to 8000rpm. However, mine was set to 2 Sec. I can see that accelerating a heavy chuck to 8000rpm in 2 sec would draw some power!

I'll have a play and see what works. I guess 4 sec is likely to reduce the draw from 20kw down to 10 - so I'll start there!

Si

[generaldisarray]

I would invest in a phase perfect converter. That voltage sag can damage the drive.
the cost of a Phase perfect is probably half of what that combined spindle/servo drive will cost to repair.

[Sterob]

Sometimes its called 'Ramp Time' and there is probably a setting for ramping up and anotehr ramping down. Sounds like your onto it anyway....

[simonrafferty]

Thanks for the lead. They look pretty good.
The problem is still that I don't have enough mains coming into the building to supply the 20Kw it requires. A better inverter (with bigger Capacitors) will be able to supply more surges without the voltage dipping - but it's unlikely to supply the additional 10kW for 5 Seconds required - Equivalent of over 200F Capacitance required! That's in the realm of Electric Vehicle Ultra-Capacitors.

I spoke to my Inverter supplier and they said, either use a bigger inverter and have a higher power mains feed installed - or reduce the current draw of the machine. Reducing the acceleration makes the most sense.

Si

[Jim Dawson]

Can you post a picture of your data plate on the machine. 27 HP seems a bit high for a Denford Cyclone, most seem to be in the <5HP range.

[simonrafferty]

Can you post a picture of your data plate on the machine. 27 HP seems a bit high for a Denford Cyclone, most seem to be in the <5HP range.

I agree it seems on the high side. The original rating plate is missing - it just has "27Hp / 50A / 415v" written on the side in black marker pen.

The inverter, being rated at 10kW but still tripping with an Over-Current error tended to confirm that it was over 10kW, at least intermittently.

Anyway, now I've turned down the parameter settings on the servo spindle controller - and it seems happy up to 5000rpm.

Thanks for your help!

Si

[Heavy_Metal]

Hi simonrafferty,

For a quick solution you can make 1 or more sub-programs for speeds above 5000 rpm.
When you need more then 5000 rpm insert an extra line in your nc-code after S5000 M03,
Put f.e. a M98 P8000 after the S5000 M03 line.
Make one or more subs like belowe, I know it's not the perfect solution but it will work.

%
O8000 ( SUB-S8000-RPM )
S6000 M03
G04 X1. ( FANUC G04 DWELL 1 SEC. - USE X OR P )
S7000 M03
G04 X1.
S8000 M03
G04 X1.
M99
%

Regards,
Heavy_Metal

[simonrafferty]

Thanks 'Heavy Metal'.
Changing the spindle parameters seems to have worked. The spindle ready line only enables when it gets up to speed, so although it's taking 2x as long, execution of the next line doesn't start until it gets up to the demanded speed.

I've only not gone above 5000 as I'm worried about the chuck making a bid for freedom! When I've got a (light, better balanced) collet chuck on the machine, I'll take it up to full speed. That said, I've rarely wanted to go much above 4000 in the past.

Si

[Heavy_Metal]

Hi simonrafferty,

Sorry, after I posted I saw it was a Lathe 0T-B, my "solution" is for a mill, you need probably the G96 instead of G97.
You can use them both to rev up the chuck/collet to 8000 rpm.

Regard,
Heavy_Metal.